Video cameras have been used to capture video images for various applications such as surveillance, machine vision, security monitoring, inspection, sensing and detection. Digital video data is processed using various computer-implemented techniques to extract useful information or to alter the video data itself. The digital video data may be sent to a nearby or remote image processing device to be processed and displayed. As the number of digital image sources increases (surveillance cameras, cell phone cameras, etc.) more capable and efficient techniques for extracting information regarding the world in near real-time are desirable.